{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T02:48:30Z","timestamp":1760150910786,"version":"build-2065373602"},"reference-count":63,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2022,1,26]],"date-time":"2022-01-26T00:00:00Z","timestamp":1643155200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100006752","name":"University of Porto","doi-asserted-by":"publisher","award":["without number"],"award-info":[{"award-number":["without number"]}],"id":[{"id":"10.13039\/501100006752","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JMSE"],"abstract":"<jats:p>To continue the investigation on the digestive system of polyplacophoran molluscs, a histological and ultrastructural study of the oesophagus, stomach and intestine of Chaetopleura angulata and Acanthochitona fascicularis was carried out. Stomach content examination revealed an omnivorous diet. In both species the epithelium of the whole digestive tract consisted mostly of elongated absorptive cells with an apical border of microvilli. Cilia were also frequently present. Mitochondria and electron-dense lysosomes were the prominent organelles in the region above the nucleus. The basal region was characterised by an association of mitochondria, peroxisomes and lipid droplets. In general, glycogen deposits were also abundant in absorptive cells. The ultrastructural features indicate that the absorptive cells of the digestive tract epithelium are involved in endocytosis, intracellular digestion and storage of reserves. Histochemical techniques showed that the secretory cells of the digestive tract contained proteins and polysaccharides in their secretory vesicles. The secretory cells with vesicles of low electron density were classified as mucous cells, and the ones with electron-dense vesicles were designated basophilic cells due to their staining by basic dyes in light microscopy. Additionally, basal cells that seem to correspond to enteroendocrine cells containing oval electron-dense vesicles were found along the digestive tract epithelium of both species. The thin outer layer of the digestive tract wall consisted of muscle cells and nerves embedded in connective tissue.<\/jats:p>","DOI":"10.3390\/jmse10020160","type":"journal-article","created":{"date-parts":[[2022,1,26]],"date-time":"2022-01-26T11:02:53Z","timestamp":1643194973000},"page":"160","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Functional Histology and Ultrastructure of the Digestive Tract in Two Species of Chitons (Mollusca, Polyplacophora)"],"prefix":"10.3390","volume":"10","author":[{"given":"Alexandre","family":"Lobo-da-Cunha","sequence":"first","affiliation":[{"name":"Department of Microscopy, Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, Rua Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal"},{"name":"Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), 4450-208 Matosinhos, Portugal"}]},{"given":"\u00c2ngela","family":"Alves","sequence":"additional","affiliation":[{"name":"Department of Microscopy, Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, Rua Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal"},{"name":"Multidisciplinary Unit for Biomedical Research (UMIB), ICBAS, University of Porto, 4050-313 Porto, Portugal"}]},{"given":"Elsa","family":"Oliveira","sequence":"additional","affiliation":[{"name":"Department of Microscopy, Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, Rua Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal"},{"name":"Multidisciplinary Unit for Biomedical Research (UMIB), ICBAS, University of Porto, 4050-313 Porto, Portugal"}]},{"given":"Gon\u00e7alo","family":"Calado","sequence":"additional","affiliation":[{"name":"Department of Life Sciences, Lus\u00f3fona University, Campo Grande 376, 1749-024 Lisbon, Portugal"},{"name":"MARE\u2014Marine and Environmental Sciences Centre, NOVA School of Science and Technology (FCT NOVA), Campus de Caparica, 2829-516 Caparica, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2022,1,26]]},"reference":[{"key":"ref_1","first-page":"55","article-title":"Polyplacophora","volume":"Volume 5","author":"Harrison","year":"1994","journal-title":"Microscopic Anatomy of Invertebrates"},{"key":"ref_2","unstructured":"Ponder, W.F., and Lindberg, D.R. (2008). Solenogastres, Caudofoveata, and Polyplacophora. Phylogeny and Evolution of the Mollusca, University of California Press."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"20190429","DOI":"10.1098\/rsbl.2019.0429","article-title":"Why do chitons curl into a ball?","volume":"15","author":"Sigwart","year":"2019","journal-title":"Biol. Lett."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Ponder, W.F., Lindberg, D.R., and Ponder, J.M. (2020). Biology and Evolution of the Mollusca, CRC Press.","DOI":"10.1201\/9781351115254"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"119","DOI":"10.1017\/S0080456800004701","article-title":"The structure and function of the alimentary canal of some species of Polyplacophora (Mollusca)","volume":"49","author":"Fretter","year":"1937","journal-title":"Trans. R. Soc. Edin."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"37","DOI":"10.1111\/j.1469-7998.1972.tb04074.x","article-title":"Feeding and gut physiology in Acanthopleura spinigera (Mollusca)","volume":"166","author":"Greenfield","year":"1972","journal-title":"J. Zool. Lond."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"655","DOI":"10.1007\/s004410050971","article-title":"The peroxisomes of the hepatopancreas in two species of chitons","volume":"290","year":"1997","journal-title":"Cell Tissue Res."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"205","DOI":"10.15298\/invertzool.14.2.16","article-title":"Anatomy of the many feeding types in polyplacophoran molluscs","volume":"14","author":"Sigwart","year":"2017","journal-title":"Invert. Zool."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"355","DOI":"10.1002\/jmor.21309","article-title":"Functional morphology of the glandular esophageal pouches of chitons (Mollusca, Polyplacophora)","volume":"282","author":"Alves","year":"2021","journal-title":"J. Morphol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"225","DOI":"10.1093\/mollus\/70.3.225","article-title":"A study on the feeding ecology of chitons using analysis of gut contents and fatty acid markers","volume":"70","author":"Latyshev","year":"2004","journal-title":"J. Moll. Stud."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"35","DOI":"10.3354\/meps07421","article-title":"Potential for omnivory and apparent intraguild predation in rocky intertidal herbivore assemblages from northern Chile","volume":"361","author":"Camus","year":"2008","journal-title":"Mar. Ecol. Progr. Ser."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"431","DOI":"10.4067\/S0718-19572013000300003","article-title":"A trophic characterization of intertidal consumers on Chilean rocky shores","volume":"48","author":"Camus","year":"2013","journal-title":"Rev. Biol. Mar. Oceanogr."},{"key":"ref_13","first-page":"55","article-title":"Carnivorous habits of two species of the genus Craspedochiton (Polyplacophora: Acanthochitonidae)","volume":"13","author":"Saito","year":"1992","journal-title":"J. Malacol. Soc. Aust."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"552","DOI":"10.1111\/1574-6941.12014","article-title":"A tale of two chitons: Is habitat specialisation linked to distinct associated bacterial communities?","volume":"83","author":"Duperron","year":"2013","journal-title":"FEMS Microbiol. Ecol."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Seto, J. (2012). The chiton radula: A unique model for biomineralization studies. Advanced Topics in Biomineralization, InTech.","DOI":"10.5772\/1095"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"411","DOI":"10.1007\/BF00220187","article-title":"Fine structure of the subradular organ of Lepidochitona cinereus (L), (Mollusca, Polyplacophora)","volume":"162","author":"Boyle","year":"1975","journal-title":"Cell Tissue Res."},{"key":"ref_17","first-page":"301","article-title":"Carbohydrate-digesting enzymes in the sugar gland juice of Cryptochiton stelleri","volume":"13","author":"Meeuse","year":"1958","journal-title":"Arch. Neerl. Zool."},{"key":"ref_18","first-page":"172","article-title":"Taxonomy of Japanese species of the genera Mopalia and Plaxiphora (Polyplacophora: Mopaliidae)","volume":"34","author":"Saito","year":"1991","journal-title":"Veliger"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1177\/26.1.74385","article-title":"Tannic acid-metal salt sequences for light and electron microscopic localization of complex carbohydrates","volume":"26","author":"Sannes","year":"1978","journal-title":"J. Histochem. Cytochem."},{"key":"ref_20","unstructured":"Ganter, P., and Joll\u00e8s, G. (1970). Histochimie Normal et Pathologique, Gauthier-Villars."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"579","DOI":"10.1177\/13.7.579","article-title":"Differential staining of ultrathin sections of Epon-embedded tissues for light microscopy","volume":"13","author":"Lane","year":"1965","journal-title":"J. Histochem. Cytochem."},{"key":"ref_22","first-page":"54","article-title":"Improvements in method for electron microscopic localization of arylsulphatase activity","volume":"8","author":"Arstila","year":"1967","journal-title":"Histochemie"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"603","DOI":"10.1071\/IS13013","article-title":"Chiton phylogeny (Mollusca: Polyplacophora) and the placement of the enigmatic species Choriplax grayi (H. Adams & Angas)","volume":"27","author":"Sigwart","year":"2013","journal-title":"Invertebr. Syst."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Kaas, P., and Van Belle, R.A. (1987). Monograph of living chitons (Mollusca: Polyplacophora). Suborder Ischnochitonina, Ischnochitonidae: Chaetopleurinae & Ischnochitoninae (pars), E. J. Brill and W. Backhuys.","DOI":"10.1163\/9789004431690"},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Ponder, W.F., Lindberg, D.R., and Ponder, J.M. (2020). Biology and Evolution of the Mollusca, CRC Press.","DOI":"10.1201\/9781351115254"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"475","DOI":"10.1007\/s00441-019-03085-9","article-title":"Structure and function of the digestive system in molluscs","volume":"377","year":"2019","journal-title":"Cell Tissue Res."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"a016857","DOI":"10.1101\/cshperspect.a016857","article-title":"The complex ultrastructure of the endolysosomal system","volume":"6","author":"Klumperman","year":"2014","journal-title":"Cold Spring Harb. Perspect. Biol."},{"key":"ref_28","first-page":"33","article-title":"The digestive system of the slug, Agriolimax reticulatus (M\u00fcller): Experiments on phagocytosis and nutrient absorption","volume":"40","author":"Walker","year":"1972","journal-title":"Proc. Malacol. Soc. Lond."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"111","DOI":"10.1093\/mollus\/55.1.111","article-title":"The ultrastructure and function of the oesophagus of Patella vulgata","volume":"55","author":"Bush","year":"1989","journal-title":"J. Moll. Stud."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1093\/mollus\/57.1.71","article-title":"Endocytosis in the crop of the slug, Deroceras reticulatum (M\u00fcller) and the effects of the ingested molluscicides, metaldehyde and methiocarb","volume":"57","author":"Bourne","year":"1991","journal-title":"J. Moll. Stud."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"3481","DOI":"10.1038\/emboj.2011.286","article-title":"Endosome maturation","volume":"30","author":"Huotari","year":"2011","journal-title":"EMBO J."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"685","DOI":"10.1111\/j.1469-7998.1988.tb02404.x","article-title":"The ultrastructure and function of the intestine of Patella vulgata","volume":"215","author":"Bush","year":"1988","journal-title":"J. Zool."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1002\/jimd.12083","article-title":"Organelle interplay - peroxisome interactions in health and disease","volume":"43","author":"Schrader","year":"2020","journal-title":"J. Inherit. Metab. Dis."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"881","DOI":"10.1016\/j.bbamcr.2010.03.013","article-title":"Be different\u2014The diversity of peroxisomes in the animal kingdom","volume":"1803","author":"Islinger","year":"2010","journal-title":"Biochim. Biophys. Acta Mol. Cell Res."},{"key":"ref_35","first-page":"255","article-title":"Peroxisomes in the digestive gland cells of the mussel Mytilus galloprovincialis Lmk. Biochemical, ultrastructural and immunocytochemical characterization","volume":"56","author":"Cajaraville","year":"1992","journal-title":"Europ. J. Cell Biol."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1007\/s004180050007","article-title":"Peroxisomes in molluscs, characterization by subcellular fractionation combined with western blotting, immunohistochemistry, and immunocytochemistry","volume":"113","author":"Cancio","year":"2000","journal-title":"Histochem. Cell Biol."},{"key":"ref_37","first-page":"299","article-title":"Lysosomes, peroxisomes and bivalves","volume":"60","author":"Owen","year":"1972","journal-title":"Sci. Prog."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"67","DOI":"10.1016\/0248-4900(94)90068-X","article-title":"The peroxisomes of the hepatopancreas in marine gastropods","volume":"82","author":"Batista","year":"1994","journal-title":"Biol. Cell"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"197","DOI":"10.1017\/S0025315417001813","article-title":"Giant peroxisomes revealed by a comparative microscopy study of digestive gland cells of cephalaspidean sea slugs (Gastropoda, Euopisthobranchia)","volume":"99","author":"Oliveira","year":"2019","journal-title":"J. Mar. Biol. Assoc."},{"key":"ref_40","first-page":"141","article-title":"Ultrastructural changes in the digestive tract of Deroceras reticulatum (M\u00fcller) induced by a carbamate molluscicide and by metaldehyde","volume":"31","author":"Triebskorn","year":"1989","journal-title":"Malacologia"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"360","DOI":"10.1002\/jmor.10099","article-title":"Stomach cells of Aplysia depilans (Mollusca, Opisthobranchia): A histochemical, ultrastructural, and cytochemical study","volume":"256","year":"2003","journal-title":"J. Morphol."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"447","DOI":"10.1016\/j.tice.2005.06.002","article-title":"Light and electron microscopy studies of the oesophagus and crop epithelium in Aplysia depilans (Mollusca, Opisthobranchia)","volume":"37","year":"2005","journal-title":"Tissue Cell"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"211","DOI":"10.1111\/j.1463-6395.2007.00268.x","article-title":"Ultrastructural, histochemical and cytochemical characterisation of intestinal epithelial cells in Aplysia depilans (Gastropoda, Opisthobranchia)","volume":"88","year":"2007","journal-title":"Acta Zool."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"32","DOI":"10.1002\/jemt.1070260105","article-title":"Structure of serous cells in salivary glands","volume":"26","author":"Tandler","year":"1993","journal-title":"Microsc. Res. Tech."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"97","DOI":"10.1002\/jmor.1052050110","article-title":"Histochemical and ultrastructural study of the alimentary tract of the freshwater snail Lymnaea stagnalis","volume":"205","author":"Boer","year":"1990","journal-title":"J. Morphol."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"387","DOI":"10.1016\/0040-8166(92)90055-C","article-title":"Intestinal cell types in the freshwater snail Planorbarius corneus: Histochemical, immunocytochemical and ultrastructural observations","volume":"24","author":"Franchini","year":"1992","journal-title":"Tissue Cell."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"39","DOI":"10.1111\/j.1463-6395.1992.tb00947.x","article-title":"Intestinal ultrastructure of Nerita picea (Mollusca: Gastropoda), an Intertidal marine snail of Hawaii","volume":"73","author":"Pfeiffer","year":"1992","journal-title":"Acta Zool."},{"key":"ref_48","first-page":"61","article-title":"Histological and ultrastructural characterisation of the stomach and intestine of the opisthobranch Bulla striata (Heterobranchia: Cephalaspidea)","volume":"27","author":"Malheiro","year":"2011","journal-title":"Thalassas"},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"49","DOI":"10.1002\/jemt.1070260106","article-title":"Structure of mucous cells in salivary glands","volume":"26","author":"Tandler","year":"1993","journal-title":"Microsc. Res. Tech."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"688","DOI":"10.1017\/S1431927610093840","article-title":"Histochemical and ultrastructural characterization of the posterior esophagus of Bulla striata (Mollusca, Opisthobranchia)","volume":"16","author":"Oliveira","year":"2010","journal-title":"Microsc. Microanal."},{"key":"ref_51","first-page":"223","article-title":"Ultrastructure of the supporting cells and secretory cells of the alimentary canal of the slugs, Lehmannia marginata and Boettgerilla pallens (Pulmonata: Stylommatophora: Limacoidea)","volume":"44","year":"2002","journal-title":"Malacologia"},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"447","DOI":"10.1126\/science.1237910","article-title":"Mucus enhances gut homeostasis and oral tolerance by delivering immunoregulatory signals","volume":"342","author":"Shan","year":"2013","journal-title":"Science"},{"key":"ref_53","first-page":"83","article-title":"Enterochromaffin (argentaffin) cells of the rat gastrointestinal tract. An ultrastructural study","volume":"92","author":"Grimelius","year":"1984","journal-title":"Acta Pathol. Microbiol. Immunol. Scand. A"},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"557","DOI":"10.1007\/BF00214576","article-title":"Ultrastructure of enterochromaffin cells and associated neural and vascular elements in the mouse duodenum","volume":"241","author":"Wade","year":"1985","journal-title":"Cell Tissue Res."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"620","DOI":"10.1111\/nmo.12754","article-title":"Enteroendocrine cells: A review of their role in brain-gut communication","volume":"28","author":"Latorre","year":"2016","journal-title":"Neurogastroenterol. Motil."},{"key":"ref_56","doi-asserted-by":"crossref","unstructured":"Guo, X., Lv, J., and Xi, R. (2021). The specification and function of enteroendocrine cells in Drosophila and mammals: A comparative review. FEBS J., epublication ahead of print.","DOI":"10.1111\/febs.16067"},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"133","DOI":"10.1016\/0016-6480(78)90155-7","article-title":"Insulin-producing cells in the gut of freshwater bivalve mollusks Anodonta cygnea and Unio pictorum and the role of insulin in the regulation of their carbohydrate metabolism","volume":"35","author":"Plisetskaya","year":"1978","journal-title":"Gen. Comp. Endocrinol."},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"185","DOI":"10.1002\/jmor.1052070209","article-title":"Presence of cells and fibers immunoreactive toward antibodies to different peptides or amine in the digestive tract of the snail Helix aspersa","volume":"207","author":"Marchand","year":"1991","journal-title":"J. Morphol."},{"key":"ref_59","first-page":"237","article-title":"Immunocytochemical detection of endocrine cells in the gut of Viviparus ater (Mollusca, Gastropoda)","volume":"38","author":"Franchini","year":"1994","journal-title":"Eur. J. Histochem."},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"15","DOI":"10.1016\/j.ygcen.2018.10.019","article-title":"Molecular evolution and functional characterisation of insulin related peptides in molluscs: Contributions of Crassostrea gigas genomic and transcriptomic-wide screening","volume":"271","author":"Adeline","year":"2019","journal-title":"Gen. Comp. Endocrinol."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"363","DOI":"10.1016\/0016-6480(88)90110-4","article-title":"Gut endocrine cells in the snail Helix aspersa","volume":"70","author":"Alba","year":"1988","journal-title":"Gen. Comp. Endocrinol."},{"key":"ref_62","doi-asserted-by":"crossref","unstructured":"Boh\u00f3rquez, D.V., Samsa, L.A., Roholt, A., Medicetty, S., Chandra, R., and Liddle, R.A. (2014). An enteroendocrine cell-enteric glia connection revealed by 3D electron microscopy. PLoS ONE, 9.","DOI":"10.1371\/journal.pone.0089881"},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"782","DOI":"10.1172\/JCI78361","article-title":"Neuroepithelial circuit formed by innervation of sensory enteroendocrine cells","volume":"125","author":"Shahid","year":"2015","journal-title":"J. Clin. Investig."}],"container-title":["Journal of Marine Science and Engineering"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2077-1312\/10\/2\/160\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T22:08:08Z","timestamp":1760134088000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2077-1312\/10\/2\/160"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,1,26]]},"references-count":63,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2022,2]]}},"alternative-id":["jmse10020160"],"URL":"https:\/\/doi.org\/10.3390\/jmse10020160","relation":{},"ISSN":["2077-1312"],"issn-type":[{"type":"electronic","value":"2077-1312"}],"subject":[],"published":{"date-parts":[[2022,1,26]]}}}